nasa eva glove characterization protocol development

48th International Conference on Environmental Systems ICES-2018-116 8-12 July 2018, Albuquerque, New Mexico

International Conference on Environmental Systems

NASA EVA Glove Characterization Protocol Development

F. Adam Korona1

NASA Johnson Space Center/Jacobs, Houston, Texas, 77058

Sarah K. Walsh2

NASA Johnson Space Center, Houston, TX, 77058

and

Shane M. McFarland3

NASA Johnson Space Center/MEI, Houston, TX, 77058

Future exploration missions involving humans will be conducted in more challenging

environments. Current Extravehicular Activity (EVA) gloves have limited life, severely limit

hand mobility and are a significant source of injury during spaceflight, making them

undesirable for future planetary exploration missions. The next generation of gloves will be

designed with the goal of significantly improving performance, such as mobility and tactility,

and tolerance of planetary environments. A multi-year effort under the High Performance

EVA Glove (HPEG) project element at NASA’s Johnson Space Center (JSC) strove to advance

the EVA glove design by developing new prototypes and establishing a glove characterization

protocol or standard to evaluate design changes. By researching hand-based test standards

from other industries and targeting common EVA glove motions, tasks were compiled and

down selected to create a set of activities to make up a standard EVA glove protocol. The

objective of the standard protocol is to allow for quantitative analysis of glove performance

data for the purpose of objectively assessing improvements among various glove designs or

iterations. The following paper describes how this protocol was used in EVA glove testing of

two new prototypes, as well as the current Phase VI Extravehicular Mobility Unit (EMU)

flight glove. In addition, it also outlines the outcome of this effort and what it means for

evaluation of EVA glove performance in the future.

Nomenclature

ASL = Advanced Suit Laboratory

CV = Coefficient of Variance

DC = David Clark Company, Incorporated

EMU = Extravehicular Activity Mobility Unit

EVA = Extravehicular Activity

JSC = Johnson Space Center

HPEG = High Performance EVA Glove

ILC = International Latex Corporation

ISS = International Space Station

MPT = Manned Pressurized Time

TMG = Thermal Micrometeoroid Garment

TS = Test Subject

1 Systems Engineer, Crew Systems and Extravehicular Activity Projects, 2224 Bay Area Blvd., Houston, TX 77058. 2 HPEG Lead FY15-FY17, Space Suit and Crew Survival Systems Branch, JSC/EC5. 3 Senior Project Engineer, HPEG Technical Lead, Space Suit and Crew Survival Systems Branch, JSC/EC5.


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I. Introduction

he current Extravehicular Activity (EVA) glove has been in service for almost 20 years, and has been used

extensively during the construction of the International Space Station (ISS). During this time, several minor

modifications and evolutions have been made to address issues and concerns along the way. The result is a very robust

EVA glove design capable of performing several complex EVAs. Future exploration missions and EVAs however,

will require the next generation of EVA gloves to function for a far greater number of EVAs with more mobility,

efficiency, crewmember protection and a decreased risk of hand injuries. To address this shortfall, the NASA High

Performance EVA Glove (HPEG) Project was initiated with the goal of furthering research and development in

advanced EVA glove design. As part of the project in 2014, a glove protocol was established to provide a basis for

evaluating glove prototypes and quantitatively comparing them to the current EVA gloves. This initial protocol used

a full pressure suit and built upon previous tasks used to evaluate EVA gloves. The 2014 protocol was a promising

pilot study, but the overhead associated with full pressure suit testing limited the number of subjects that could be

used in a reasonable timeframe. The protocol was therefore adjusted to use a glovebox instead of a full suit, which

decreased testing overhead, and increased the number of subjects who could be easily tested. This paper discusses the

early development of the glove performance protocol, the EVA glove tasks evaluated for the final NASA HPEG EVA

glove protocol testing which was completed in 2016, test results and conclusions on advancing future glove protocols.

II. Test Objective

This test series had two primary objectives. The first objective was to validate the new glove performance protocol

that had been identified and pilot tested at the beginning of the HPEG project, using two new prototype gloves and

the current Phase VI EVA glove with a test sample size suitable for statistical analysis. Ideally, a new glove protocol

would emerge as a standard under which all new EVA gloves could be evaluated. The second objective was to

evaluate the performance of the new HPEG prototype gloves against the currently-flown Phase VI glove.

III. Early Protocol Development

Early development of the glove protocol first focused on an extensive market survey and research. The principal

investigators looked at historical attempts to evaluate glove performance, as well as hand-based testing standards from

other industries. Candidate protocol tasks were identified and evaluated for applicability, feasibility, time, etc. The

best candidates were then carried forward into a suited pilot study in 2014. The individual tasks that were considered

for this testing included the following:

Gloved Grip Strength

o Grip dynamometer (NASA previous use)

Gloved Mobility

o Simple Thumb Opposition (Thompson 2011)

o Thumb Pollexograph (Kraker et al 2009)

o Modified Kapanji Index (Lefevre-Colou 2003)

o Standard finger Goniometer (Macionis 2013)

o Delta Finger-to-Palm (Torok 2010)

o Paper Goniometer (Macionis 2013)

o Wrist goniometry (Horger 1989, LaStayo 2004)

Gloved Tactility

o Shelby Block Test (NASA previous use)

o Two-edge discrimination (O’Hara 1988)

o Grip Force Perception (O’Hara 1988)

Gloved Dexterity

o Cutkosky Taxonomy (Cutkosky 1990)

o Mudras postures (Vipin 2008)

o Purdue Peg Board (Yancosek 2008)

o Modified Purdue Peg Board (O’Hara 1988)

o Nut-and-Bolt Test (O’Hara 1988)

o Cylinder Pickup Test (NASA previous use)

o Minnesota Manual Dexterity Test (Yancosek 2008)

T


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o Functional Dexterity Test (Dorit 2003)

o 9-Hole Pegboard (Mathiowetz et al 1985)

o Workability Rate of Manipulation Test (King 1998)

Gloved Comfort

o ILC/Grumman Comfort Scales (Hinman-Sweeney 1994)

o Glove Comfort Evaluation Forms (O’Hara 1988)

Gloved Fatigue

o Electromyography (O’Hara 1988)

o Subjective metrics (O’Hara 1988)

o Performance decay, total work (O’Hara 1988)

o Performance degradation on a dynamic gripping task (Hinman-Sweeney 1994)

o Sustained contraction, static gripping task (Bautmans et al 2007)

Gloved Fit

o Canadian Glove Fit Survey (Weihrer 2000)

o Functional Fit evaluation (Tremblay-Lutter 1995)

o Silhouette measurement (new)

o Anthropometric comparison of subject to the crewmember that the glove size was designed for

Gloved Pinch Strength

o Key Pinch Strength (NASA previous use)

o Pulp Pinch Strength (NASA previous use)

A subset of these tasks were selected to move forward into two pilot studies in 2014; first in a glovebox and then

in a full suit. Thorough investigation of the resulting data and the logistical impacts of each task evaluated resulted in

a final set of performance tasks outlined in Section V. The final set of tasks evaluated in this protocol included a single

task for each of the comfort, fit, tactility, and grip strength categories, and three metrics each for dexterity and mobility

catagories. Fatigue and pinch strength were not selected to be evaluated going forward.

IV. Test Plan Overview

In the final permutation of the protocol, seven test subjects were used, with each subject performing various glove

box tasks using three different gloves. The tasks performed in this test series were based on the glove performance

task executed in the joint 2014 Biomedical Research and Environmental Science Branch and the Crew and Thermal

Systems Division study. The 2014 study tasks were modified to accommodate testing in a glove box instead of using

a full pressure suit. The decision to test in a glove box instead of a fully pressurized suit was made primarily due to

the increased overhead associated with a fully pressurized suit run. By performing tasks in a glove box, the number

of test subjects and the number of test sessions could easily be increased to improve statistical significance without

additional overhead. This approach also facilitates easier access to protocol testing by organizations who may not have

a full suit but do have access to a glovebox.

The tasks used in this study were intended to help characterize glove grip strength, tactility, mobility and dexterity.

These tasks included using a hand dynamometer, picking up cylinders of various diameter, relocating pegs on a

pegboard, identifying gaps between a ruler, tying knots, and being able to touch various locations on each glove.

V. Test Method

The glove tasks characterization tasks used in this study included various dexterity, tactility, grip strength, and

mobility tasks, which are listed in the following subsections. Comments on overall discomfort, fit and usability were

also collected at the end of each test session. The complete test session was conducted from start to finish with a single

glove configuration. Most tasks were performed with and without a TMG unless specifically noted to more fully

characterize each glove. The order that each glove was tested was randomized among test subjects to help address the

impacts of any learning curve.

Test subjects were selected based on hand size, and grouped into one of two glove sizes. Custom glove fit checks

were then performed to ensure each subject had a good fit. Familiarization sessions (fam session) were provided for

each test subject to provide them with an overview of the test and tasks that they would perform. The following

sections describe each task performed in the order tested.


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A. Grip Strength

Grip strength is considered to be a strong candidate for inclusion in an objective performance metric, because previous

tests have shown data to be repeatable within a given test configuration, and marked performance deficits can be

shown between an ungloved and a gloved state. A Jamar hydraulic dynamometer was used to obtain this grip strength

data. Without the TMG, dry run test subjects commented early on that it was extremely difficult to hold the

dynamometer in an appropriate posture to capture meaningful data. When the glove undergoing testing was in a non-

TMG configuration, the grip strength task was skipped. For this task, three attempts were performed unless the

Coefficient of Variance (CV) was greater than 10%. If CV was greater than 10%, additional attempts were conducted

until the CV was decreased to 10% or less. Photos of the Grip Strength task are shown in Figure 1.

Figure 1: Grip Strength Task

B. Mobility

Mobility tasks consist of cylinder grasp and index finger, middle finger, and thumb reach tasks.

The cylinder task was used to evaluate how each glove could be used to grasp an object. This task was selected due

to its ease of use and relative applicability to typical EVA tasks (handrail translation, etc.). In addition, the ability to

“palm” an object was thought to be a challenging yet reasonable proxy for overall mobility of grasping tasks. To

complete the task, test subjects would pick up one cylinder at a time and then turn his/her hand over showing they had

control of the cylinder, as shown in Figure 2. Seven cylinders of different diameters (5/8”, 1 1/8”, 2 ½”, 2 7/8”, 4 ½”,

5”, and 6”) were used for this task. Since this task is dependent on the grip of the TMG or cover layer, this task was

only performed for the TMG configuration of each glove.

Figure 2: Cylinder Task

Reach tasks involving the index finger, middle finger and thumb are considered modifications of the Kapanji Index

(Lefevre-Colou 2003) and aim to evaluate the range of finger/thumb motion of test subjects. These tasks were chosen

to allow for a binary yes/no of the ability for a subject to manipulate a digit to the extremes of the hand workspace; in

addition, it is easy to implement and requires no special hardware. Figure 3 shows the targeted points (1-5 or 1-11)

that the starred finger/thumb tip aims to contact. Examples of test subjects performing the middle finger reach task

are shown in Figure 4.


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Figure 3: Index Finger, Middle Finger and Thumb Targets

Figure 4: Middle Finger Mobility

C. Tactility

Tactility data was collected using a device that was inspired by techniques for evaluating cold weather hand protection.

This task measures glove tactility by evaluating the ability to distinguish surface features by touch. It was chosen over

other tactility tests because in addition to its relative simplicity, it also incorporates evaluation of false positives. The

test involves placing two straight edges next to each other with the ability to adjust the angle between them. With

their eyes closed, test subjects were verbally guided to tap their index finger along the straight edges in one inch

increments. At each tap, the test subject was asked if they could feel a gap. The process was done 6 times with the

angle of the rulers varied between each attempt. Examples of a test subject placing a gloved finger over different

sized gaps is shown in Figure 5.

Figure 5: Tactility Task


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D. Dexterity

Three dexterity tasks were included in the protocol, pegboard, knot tying and bow tying, each involving timed trials

of a particular hand maneuver.

The pegboard task involved test subjects picking up a U-bolt, turning it 90 degrees, placing it back into the pegboard,

and proceeding to the next U-bolt until all 10 U-bolts have been repositioned. Tests subjects began with the U-bolts

located on the bottom row, moving from left to right and then proceeded to the U-bolts on the top row, moving from

left to right. The total task time was recorded and then repeated two more times for a total of three trials. This task

was chosen due to its similarity with the standard method of the Purdue Peg Board, but with modifications to allow

for gloved operations, including a larger gauge pin, and a rotation element that would tax the wrist mobility of the

glove. Sample photos of test subjects performing the task are shown in Figure 6.

Figure 6: Pegboard Task

Knot and bow tying tasks were implemented due to their inherently difficult and complicated nature, as an attempt to

evaluate completion time of performing a complicated multi-step task that required a combination of dexterity, tactility

and mobility. The knot tying task required test subjects to tie five overhand knots. This was repeated until three trials

were completed. Subjective comments and task completion times were taken for each trial. Examples of test subjects

performing this task are shown in Figure 7.

Figure 7: Knot Tying Task

The bow tying task required test subjects to tie and untie a standard knot and bow. This task was repeated until three

trials were completed. Subjective comments and task completion time were taken for each trial. Examples of Test

Subjects performing this task are shown in Figure 8.

Figure 8: Bow Tying Task


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E. Discomfort

Discomfort data was collected at the end of each test session, when a subject was expected to have a good indication

of where areas of discomfort existed. Discomfort is viewed as an importance metric to track, as it not only affects

crewmember performance and efficiency, but is a potential precursor to crew injury. Test subjects were asked to note

locations of discomfort, and to indicate the type of discomfort (e.g. chafing), and the magnitude from barely noticeable

to unbearable. The scale and guidelines associated with contact type and discomfort intensity are shown in Figure 9.

Figure 9: Hand Discomfort Contact Type and Intensity Rating Scale

F. Fit

Fit, like discomfort, was assessed using a questionnaire. The questionnaire was given before testing commenced, as

well as after testing had been completed.

Nominally, fit is not a comparative metric across glove designs, aside from indicating how well a particular glove

design can be fit to its intended population. These kinds of comparisons can only be made if all compared gloves

were built to fit that population. Nevertheless, no glove fit is perfect in every hand posture, and different design

components may also lead to unforeseen fit issues that may have an effect on performance. In other words, poor fit

should be documented due to its impact on performance, as well as to determine how well a glove design is fitting its

population. This metric provides details about the effectiveness of an existing glove design, and may point out areas

that need to be improved.

G. Post Test Questionnaire

Following each glove test, subjects were asked to provide feedback on the glove’s overall performance in a variety of

categories: discomfort, fit, dexterity, tactility, grip, fatigue and overall usability. For each of the categories, test

subjects were asked to provide a rating from 1 (extremely poor) to 7 (extremely good). Subjects were also asked a

series of open-ended questions to give subjects an opportunity to describe issues or strength associated each of the

gloves. The questionnaire was meant to catch differences in performance that may have been more subjective, as well

as to help explain any deficiencies evident in the quantitative performance metrics.

VI. Test Hardware Description

A. Gloves Evaluated

Testing focused on three glove types: the Phase VI glove that is currently used on EVA, the prototype ILC High

Performance EVA glove (HPEG) and the prototype David Clark Phase VII. Pictures of all gloves used in this study

are shown in Figure 10.

Contact Type Intensity

N/A - Not Applicable N/A - Not Applicable

1 - Touching 0 - Nothing at all

2 - Pressure Point 0.5 - Extremely weak

3 - Pinching 1 - Very weak

4 - Chafing 2 - Weak (light)

5 - Thermal 3 - Moderate

6 - Other 4 - Somewhat strong

5 - Strong (heavy)

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7 - Very Strong

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10 - Extremely strong


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Figure 10: Gloves Tested: Phase VI (left), ILC HPEG (center), DC Phase VII (right)

All gloves were tested at 4.3 psid regardless of their maximum operating pressure. Two sizes of each glove design

were tested in both a Thermal Micrometeoroid Garment (TMG) (or volumetric equivalent) and a non-TMG

configuration.

Because hand measurements can vary significantly across a population, and because individual finger dimensions are

also highly variable (even between the left and right hands of the same individual), a good glove fit can be difficult to

achieve. A poor glove fit can initially lead to discomfort (due to pressure points, for example) and a lack of

performance. Over the duration of an EVA, this discomfort can lead to increased fatigue and even short or long term

hand injury. Even if a glove does not cause discomfort, a glove finger that cannot be sized short enough for example,

may restrict a subject’s ability to perform fine motor skills with the fingertips. EVAs in general are filled with hand

intensive tasks ranging from nominal airlock operations to configuring cables and orbital replacement units, so any

decrease in hand/glove performance caused by increased fatigue or injury can quickly put an EVA or a crewmember’s

life at risk.

To ensure each test subject had a proper glove fit, hand measurements were taken and then compared against available

glove sizes. Once a glove size was selected, finger lengths were adjusted to provide the best achievable fit in that

glove. Optimal glove fit for each subject was verified during a standard glove fit check, prior to their data collection

session in each glove.

1. Phase VI Glove

The Phase VI glove was first flown in 1998 and was designed to be custom manufactured for individual crewmembers.

Originally each individual obtained a pair of gloves that were specifically designed and built for their hands. Since

the time when these gloves were originally flown, several minor modifications have been made to these gloves and

they remain the main glove used in EVAs today. With the number of custom sizes increasing over time, the hand

sizes of newer crewmember usually fell within one of the existing glove sizes. One of the existing gloves were then

sized appropriately to allow the newer crewmembers to have an acceptable glove fit. One pair of MA and one pair of

FO size Phase VI gloves were used for this test series.

2. ILC HPEG Glove

The ILC HPEGs were designed and fabricated by ILC Dover. These developmental gloves were designed and

fabricated to be a high mobility, 8.3 psid prototype spacesuit glove. The ILC HPEG glove architecture is an evolution

of the current ISS EMU Phase VI EVA Glove, and has a similar restraint and bladder system as the current Phase VI

glove with the major exception of the thumb carpometacarpal joint. This new joint utilizes a dual ring rolling convolute

for improved mobility. The wrist softgoods are the same as Phase VI but the wrist hardware has been redesigned to

incorporate hard middle and lower primaries. These provide increased strength and potentially improved cycle life.

The wrist secondary axial restraints are identical to those used on Phase VI. The thermal micrometeoroid garment

contains new materials and incorporates patterning changes over the Phase VI design as well as improved

manufacturing techniques. Sizing for the ILC HPEG gloves were similar to the Phase VI. The ILC HPEG HMA and

HFO sizes used for this test series roughly corresponded to the Phase VI MA and FO sizes.


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3. DC Phase VII Glove

The two pair of DC Phase VII development gloves were designed and fabricated by the David Clark Company,

Worcester MA. The DC Phase VII (small) was originally used in the 2014 glove study. A second similar but larger

pair of DC Phase VII (large) were delivered in mid-2016. The DC Phase VII (large) fit a larger sized hand population

and included several improved features over the DC Phase VII (small). Some of the improvements in the DC Phase

VII (large) included a flocked urethane bladder to improve don/doff, a laser sinter ‘palm cage’, and castable Silicone

nylon mesh finger caps. The DC Phase VII (large) has a simplified cover-layer rather than a full TMG. The DC Phase

VII (small) TMG and DC Phase VII (large) cover-layer look similar, however there are some difference such as

surrogate materials used in place of Aerogel and Mylar, that make the cover-layer lower fidelity. For simplicity, the

DC Phase VII (large) cover-layer will be referred to as a TMG in this test report.

B. Glovebox

All test sessions were performed in the Johnson Space Center (JSC) Advanced Suit Laboratory (ASL) glove box

shown in Figure 11, at a pressure differential of 4.3psid. Lower arms connect to the two fixed side mounts. The glove

box can be adjusted lower or higher to accommodate varying test subject heights.

Figure 11: JSC ASL Glove box

VII. Data Analysis

A. Dexterity Testing

The data presented in this section was derived from the raw test data for simplicity and brevity. A separate statistical

analysis effort was performed using the analysis of variance and was performed by the SAS software general linear

models procedure (SAS Proc GLM). The statistical analysis showed that the performance times of all glove were

statistically similar.

The test protocol included three different dexterity tests: pegboard, knot tying, and bow tying. Each requires different

types of motion on the part of the wearer. To alleviate potential learning effects, the average of the minimum

completion times across test subjects was used to compare timed tasks. Figure 12 shows a comparison of dexterity

task completion times for barehanded and TMG configurations of the Phase VI, ILC HPEG and DC Phase VII gloves,

along with standard deviation bars. The relatively high standard deviations indicate that the minimum completion

times across test subjects varied substantially and there are no statistical differences between the three gloved test

cases.


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Figure 12: Dexterity Completion Time Summary Chart (w/ TMGs)

B. Tactility Testing

For the gap detection task using gloves with a TMG there appeared to be no significant difference when comparing

the two advanced prototype gloves to the Phase VI glove. When making the same comparison without a TMG there

is even less variation.

This task required the test conductors to use the pressurized gloves to reconfigure the test setup between trials, which

was expected to be difficult and time consuming. The execution of this task was easier than expected, however this

task did not highlight differences between gloves in this test. Future glove tactility testing may consider either using

another method, or modifying this method in some way to highlight tactility differences between gloves.

C. Grip Strength

The percent of ungloved grip strength for all three gloves tested was fairly similar and within standard deviation. All

grip strength data for pressurized gloves is less than that of the barehanded trials, which is expected due to the increased

bulk caused by the TMG. Some small differences between glove types may be observed, but once standard deviations

are included for the data, all three gloves appear to be similar.

D. Mobility

Two types of mobility tasks were included in this test series: cylinder pick-up and finger touches. The first involved

test subjects picking up cylinders of various sizes and demonstrating control of the cylinder. The second set of

mobility tasks use the modified Kapandji protocol. The modified Kapandji protocol uses a ranking scheme to rate the

locations a subject can reach on their own hand. The current protocol was modified to be performed with an EVA

glove, but uses the same basic concepts. Glove mobility is presented in terms of the closest and most distant point

that can be reached on the hand, with a numeric rating provided for each location.

1. Mobility: Cylinders

The results for each test subject are shown below in Figure 13. Picking up and controlling the largest cylinder were

successfully completed by all barehanded test subjects, while only one of seven test subjects was able to pick up the

largest cylinder (6 inch diameter) while gloved. None of the test subjects were able to control the largest cylinder (6

inch diameter) with any of the gloves tested. Test subjects using the DC Phase VII glove could not pick up or control

any cylinder greater than 2 7/8” in diameter. Several test subjects commented that the DC Phase VII TMG seemed

‘slippery’ compared to the other gloves and that the thumb seemed to be biased more in flexion than other designs,

making it hard to extend the thumb grasp for larger cylinders. The cylinder pick-up and control task appears to be

good at evaluating finger extension, but may be highly dependent on the TMG design and ‘stickiness’. In the future,

the weight of the cylinders might be increased (and made equal across cylinder sizes) to decrease the reliance on the


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‘stickiness’ of the TMG, and focus more on the extension of the fingers. Another recommendation is to use similar

weighted, but varying sized spheres instead of cylinders for this task.

All test subjects could easily pick up the 5/8” and 1 1/8” cylinders with each glove, so future testing may consider not

including these two smaller cylinders. Additional incremental sizes of cylinders between the larger sized cylinders

may be added to help differentiate the largest cylinder picked up and/or controlled.

Figure 13: Maximum Cylinder Size Picked up by Glove Type

2. Mobility: Index Finger, Middle Finger, and Thumb Reach Ratings

All test subjects were able to touch every point in both the middle and index finger mobility tasks with and without a

glove. There was almost no difference in middle finger mobility scores between glove types. This may be due to the

limited performance that can be gained from one glove to another when only looking at a single axis joint. Other

methods of evaluating the entire glove system or even joint torques may be more useful. Future testing may decide

to not use the middle or index finger mobility tasks unless there is a real concern that a specific design limited middle

finger mobility.

The thumb reach mobility for each glove is shown in Figure 14, and all appear to be similar with the DC Phase VII

having slightly greater range between the highest and lowest points reached. The increased mobility for the DC Phase

VII may be due to the LinkNet mobility feature in this glove design. The incorporation of a dual ring rolling convolute

thumb joint in the ILC HPEG was assumed to increase thumb mobility over the Phase VI. This modification resulted

in 5 of 7 test subjects having greater range of thumb motion away from the thumb, but at a cost of a decreased range

of motion near the thumb for all test subjects. On a whole, the data collected from the thumb reach task was varied

across both subjects and gloves without any consistent trend. Future testing may decide to not use the thumb mobility

task unless there is a real concern that a specific design limited thumb mobility.


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Figure 14: Mobility – Thumb Reach Ratings

E. Discomfort

While the quantitative data presented above identified little if any differences between gloves, the discomfort data

highlighted areas of discomfort ranging from nothing to strong intensity discomfort. The resulting data for each glove

and test subject is shown below in Table 1. The majority of the subjects had little to no comments related to the finger

lengths, finger circumference or finger crotch discomfort. This suggests that the gloves were properly sized for each

subject based on current sizing methods which focus on fingertip and finger crotch contact. The majority of discomfort

comments were related to the hand itself, especially in the knuckle region. In general there appeared to be a correlation

between glove fit and discomfort especially in the knuckle region. The David Clark Phase VII glove for example had

a non-adjustable palm cage, which resulted in very little discomfort for test subjects having a ‘good fit’, but resulted

in significant discomfort for any subject not having an ideal fit. This discomfort may have had an impact on

performance times of complex tasks like the knot tying or bow tying. Each glove box test session was approximately

two hours in length. If these tasks were continued for a longer period of time to more closely simulate a full six hour

EVA, the intensity ratings may increase, and performance times may slow even more. Future glove designs should

therefore continue to refine the hand/knuckles area. This subjective data provided some insight into each test subject’s

discomfort for each glove, but future test series may want to capture discomfort ratings at the end of each individual

task instead of only at the end of a test session. This may help identify discomfort associated with certain tasks and/or

motions for each glove design.


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Table 1: Discomfort Intensity Ratings for Each Glove, by Subject

F. Fit

Fit ratings were obtained at the beginning and the end of each glove session for each test subject in each glove

configuration. For the Phase VI and ILC HPEG, test subjects generally commented that the fit was ‘just right’ or

slightly too large. When looking at the test subjects that commented having a fit other than ‘just right’, the majority

for Phase VI and ILC HPEG were in the small hand test subject pool (TS4, TS6 and TS7). Test subjects generally

commented that the initial fit of the DC Phase VII was also ‘just right’ with only TS2 and TS5 stating that several

portions of the glove was slightly too large.

After looking at the initial and final fit rating it became clear that some test subjects changed their opinions of their

glove fit. To more easily see which aspects changed from the initial and final fit questionnaire, Table was created to

highlight the differences. An “X” is shown in this table when any change in scoring occurred between the initial and

final fit rating.

Glove Size: TS1 TS2 TS3 TS4 TS5 TS5 TS6 TS7 TS1 TS2 TS3 TS4 TS5 TS6 TS7 TS1 TS2 TS3 TS4 TS5 TS6 TS7

Thumb Length 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Index Length 0 0 0 0 0 0 0 0.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Middle Length 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Ring Length 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Pinkie Length 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Thumb Circ. 0 0 0 0 0 0 0 0 1 0 0 0 3 2 0 1 0 0 0 0 0 0

Index Circ. 0 0 0 0 4 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Middle Circ. 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Ring Circ. 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Pinkie Circ. 0 0 0 2 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1

Crotch 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 0 0 3 0 0 0 0

Crotch 2 0 0 0 0 0 1 2 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Crotch 3 0 0 0 0 0 0 3 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Crotch 4 0.5 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Knuckles 0 0 0 0 4 0 0 1 0.5 4 3 4 0 6 3 0 4 3 0 3 3 0

Upper Palm 0 0 0 0 0 0 0 0.5 0 0 0 0 3 0 0 0 0 0 0 0 5 0

Lower Palm 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0.5 1 4 0 0 3 0 0

Top of Hand 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 3 0 0 0 0

Wrist 0 0 2 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 0 0 2

Overall 0.5 0 0 0 4 0 1 0 0 4 2 0 1 0 3 0 4 0 0 3 2 0

Phase VI ILC HPEG DC Phase VII


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Table 2: Differences between beginning and End of Session Glove Fit

The majority of test subjects providing different fit ratings between the beginning and end of the session shown in

Table 2 had the least amount of pressurized glove box experience (TS5, TS6 and TS7). This rough correlation

between the level of experience and ability to provide commentary on glove fit should be taken into account in future

pressurized glove box testing.

G. Post-test Questionnaire

At the end of each test session subjects were asked to provide subjective feedback on a number of performance factors

on a scale of 1 to 7 with 7 being the most desirable. When looking at a summary of these scores in Table , neither of

the new prototype gloves are viewed to outperform the Phase VI glove by test subjects in any category.

Subject were also asked to provide any additional comments at this time. These comments ranged from comments on

the ‘natural motion’ of the DC Phase VII glove wrist, to the DC Phase VII bulky finger caps, the impingement felt at

the base of the ILC HPEG thumb, to which glove was the easiest to don and doff. With all the data collected in this

study, these subjective comments appeared to provide some of the best feedback to help identify glove strengths and

areas of improvement. This subjective data provided some insight into how the test subjects felt each glove performed

overall, but future test series may want to capture performance ratings at the end of each individual task instead of

only at the end of a test session. This may help identify performance benefits associated with certain tasks and/or

motions for each glove design.

TS1 TS2 TS3 TS4 TS5 TS5 TS6 TS7

Size: MA MA MA FO FO MA FO FO TS1 TS2 TS3 TS4 TS5 TS6 TS7 TS1 TS2 TS3 TS4 TS5 TS6 TS7

Thumb Length X X n/a X X

Index Length X n/a X X X

Middle Length X X X n/a X X X

Ring Length X X n/a X X X X X

Pinkie Length X n/a X X X X

Thumb Circ. X n/a X X

Index Circ. X n/a X

Middle Circ. X n/a X

Ring Circ. X n/a X

Pinkie Circ. X X X n/a X X X

Crotch 1 n/a X

Crotch 2 n/a X

Crotch 3 X n/a X

Crotch 4 n/a X

Hand Circ. X X n/a X

Wrist Circ X X X n/a X

Overall Fit n/a X

Phase VI ILC HPEG DC Phase VII


15

Table 3: Averages of Overall Post Test Subjective Feedback

VIII. Discussion

At the beginning of this test series it was expected that the two advanced development glove designs would outperform

the current Phase VI glove in glove box testing using the proposed test protocol. The data collected during this test

series did not show significant improvements by either advanced prototype design when compared to the current Phase

VI glove. In an attempt to better understand any glove performance differences, several small studies were performed.

The following section discusses potential sources of error and discrepancies.

A. Day-to-Day Variability

Unlike mechanisms, human performance varies from day-to-day based on a number of factors. These factors could be

physical or even emotional. Test subjects may be more motivated on one day compared to the next, or more careful

on one day compared with next. In both cases, the resulting task performance times could be affected. This test series

did not focus on evaluating the human variability associated with these tasks, but in one case, data was captured

showing an example of this variability. This example is included merely to illustrate potential variations, and should

not be used to derive specific conclusions. Two almost complete sets of data were captured on Test Subject #2’s

(TS2) use of the DC Phase VII glove. During TS2’s initial DC Phase VII glove session, the DC Phase VII glove failed

towards the end of the session. As a result, the entire DC Phase VII session was repeated once the glove was repaired.

This subsection presents data from TS2’s initial and repeat DC Phase VII sessions to provide an example of day-to-

day HPEG data differences for the same test subject.

The finger reach and cylinder task results for both trials were the same, and the grip strength was similar (65 lbs. on

initial session vs 60 lbs. on repeat session) for each session. Table shows the pegboard and knot task minimum

completion times for TS2’s initial and repeat the DC Phase VII test session. For the performance tasks, the completion

times were all slower during the repeat session by ~41%.

5.6 4.1 4.7

5.3 5.1 5.4

5.1 4.9 5.3

5.0 4.4 3.7

4.5 4.6 3.0

5.3 5.0 4.1

5.5 5.6 4.4

4.5 4.3 5.1

5.1 4.9 4.6

A: Overall Discomfort Level

B: Overall Fit

C: Dexterity (ability to move hands)

D: Tactility (overall)

E: Tactility (at Fingertips)

F: Grip with Fingers and Palm of hand

G: Pinch and Grasp with Fingertips

H: Overall Fatigue

I: Glove Usability Overall

ILC

HP

EG

DC

Ph

ase

VII

Ph

ase

VI

Overall Averages


16

Table 4: Test Subject 2 Day-to-Day Variability in the DC Phase VII (Large) Gloves

Minimum Pegboard task

completion time

% difference

Minimum Knot task completion time

% difference

Initial Session (with TMG on) 33.4 58.8

Repeat Session(with TMG on) 39.2 17% 83.4 41%

Initial Session (with TMG off) 25.1 57.6

Repeat Session (with TMG off)

30.9 23% 61.3 6%

There are several potential reasons for the differences between the initial and repeat test session performance times.

First, the repeat session was conducted ~100 days after the test subjects previous glove box session, whereas the first

four sessions (including the fam session) were all completed within 30 days, so there may be some ‘unlearning’ or

test subject ‘staleness’ resulting from this time lapse. A second fam session prior to the repeat session may have

helped decrease any ‘unlearning’, which may have occurred.

It should be noted that test subject 2 tended to have the greatest variability of any of the test subjects used, so using

TS2 as the subject to characterize day-to-day variability may be assuming a greater than average variability. In

addition, while this variability assessment was completed on one particular glove design, the authors do not feel that

performance variability would be appreciably different with another glove.

B. New versus Old Gloves

When using the current phase VI gloves, the crewmembers have commented on a break-in period associated with

EVA gloves. These crew members have commented that new gloves are much ‘stiffer’ than ones with tens or hundreds

of hours on them. For flight gloves, ILC Dover nominally performs a break-in cycling of gloves prior to every flight

glove delivery since 1981 to reduce torque. The current Phase VI gloves for example have an equivalent of 23 hours

of break-in cycles performed before being delivered, which is 5% of the glove’s operational life. This is done by

performing 2116 finger flex (hand clinch and open cycles) and 1058 wrist flex/ex and 1058 wrist ad/ab cycles (Splawn,

2016). If newer gloves are indeed significantly stiffer than old gloves, glove performance may also be impacted.

In this test series, the Phase VI gloves have over 100 hours of manned pressurized time (MPT) use and would be

considered to be well broken-in. The Phase VII and ILC HPEG gloves were still fairly new gloves with an estimated

5 and 20 hours of MPT each prior to testing. The scope of this test series did not include evaluation, or even identifying

the MPT of each pair of gloves, which may have a significant impact on glove performance. Another test series with

additional gloves at the same MPT level would be needed to sufficiently characterize the changes in performance and

mobility as a function of MPT.

C. Effect of Hand Size on Glove Performance

Each glove used in this study was designed to fit a specific anthropometric range of hand dimensions. At the beginning

of this test series test subjects were selected and assigned to either a small or large glove size pool based on the their

anthropometric dimensions. A large number of potential test subjects were turned down due to their hand size being

outside the acceptable range for the gloves being tested. Each test pool had their own set of gloves with the same

design and construction, just a larger or smaller version of the glove. After determining which glove size was

appropriate for each test subject, an individual fit-check and adjustment was performed to ensure each test subject had

a ‘good’ glove fit. One test subject (TS5) was initially selected for the small hand pool, but was unable to physically

fit into the DC Phase VII (small), and therefore used the DC Phase VII (large), during testing. TS5 data is still used

in most overall comparisons, but will be removed from the discussion in this subsection to focus on three test subjects

in the large hand pool (TS1, TS2 and TS3) and three from the small hand pool (TS4, TS6 and TS7).

One difference between the two test subject pools is grip strength, as shown in Figure 15. While there does appear to

be a difference in grip strength between each pool, the differences within each pool appear to be fairly small. The

large hand group does appear to have slightly less test subject-to-test subject variances, which may suggest having a

higher overall grip strength may overcome any performance related decreases associated with a specific glove design.


17

Figure 15: Mean Grip Strength per Hand Size

In addition to grip strength, actual performance times also appear to be different for each subject pool as shown in

Figure 16 for the pegboard task (w/ TMG). The small hand pool appears to perform equally or slightly better in the

advanced prototype gloves, while the performance in the large hand pool appears to be slightly worse (but within the

error range) for the two advanced prototype gloves. Further review of each test subjects performance follows a similar

trend with TS4 showing substantial decrease in performance time in the DC Phase VII when compared with the other

gloves, is opposite of every other test subject. This data suggests that hand size and potentially glove fit has a greater

impact on glove performance than the targeted performance enhancements of each advanced prototype glove.

Figure 16: Average Minimum Pegboard Task Times per hand Size

D. Glove Box versus Fully Suited Evaluations

In 2014 a previous HPEG glove test was performed similar tasks using a full pressure suit instead of a glove box. The

2016 study attempted to look into how performing these tasks in a different setup may affect test results. The 2014

data was therefore analyzed in two different ways in this study. The 2014 data was first analyzed by itself using

methods similar to those described in section 4.0, and then compared against results from this study. When only

analyzing the 2014 performance times, all 2014 gloves data yielded statistically similar performance times. Next, an

attempt was made to compare the 2014 test results to the results obtained in this study. Unfortunately there were

enough procedural differences between these two studies that made comparison of the data impractical. In the 2014

study for example, test subjects had to tie as many knots or bows in a given time, whereas the 2016 subjects were

asked to complete a specific number of bows or knots and the overall completion times were recorded. Even if the


18

same tasks were used, there are inherent differences between performing glove tasks in a glovebox versus a full

pressurized suit. Some of these differences are discussed below.

The glove box used in this test series was not adjustable to conform to specific test subject anthropometric needs with

the exception of glove box height. Several subjects commented on sore biceps due to the width of the glove box

shoulders, and several subjects who had participated in the full pressure suit tests in the past commented that

performing the same tasks in a glove box seemed to be more difficult when compared to the full pressure suit

experience.

Additionally the wrist-to-fingertip and wrist-to-index middle finger crotch lengths for each glove tested was different,

as shown in Table 5. In full suit testing this is offset by adding sizing features to ensure the elbow joint breaks at a

natural place. In this test series, all test subjects used the same arm segments for all gloves, without any unique sizing.

This may have affected arm mobility and hand placement inside the glove during each task. Conducting this test in a

well-sized full pressure suit or ensuring proper arm and elbow sizing for future glove box testing may have an impact

on performance times.

Table 5: Glove Lengths

The current glove box version of this test protocol was not fully validated against the full pressure suit equivalent

tasks. Additional testing having test subjects perform the same HPEG tasks in a full pressure suit and in a glove box

would be helpful in better understanding the differences and help fully validate a glove box version of the HPEG test

protocol.

IX. Conclusion

This test series showed that while the quantitative performance data, in general, did not show differences between

gloves, test subjects were able to distinguish notable strengths and weaknesses of each glove. Users were able to

subjectively comment on things such as ease of use, comfort, fit and fatigue. In some instances, they were able to

detect competing traits and provide judgement on what should have the higher priority. For example, some new design

features provided a greater range of motion, but came at the expense of comfort. Comfort is inherently subjective, but

is none the less, a critical component in glove design. Future gloves need to include enough sizing options for various

glove components in order to obtain a ‘good’ fit to minimize discomfort. Input from the user is required to determine

if the decreased comfort is worth the mobility benefit. When one of the largest factors in glove performance is how

the user feels in the glove, it is important to allow for that to have a significant influence.

One of the key challenges in obtaining statistically significant test results from the glove protocol is human variability.

Small differences were seen between test subjects and tasks, but the largest variability ended up being the test subjects

themselves. While this conclusion may seem to lead to the option of glove testing using robotic hand surrogates for

repeatability, this concept undoubtedly brings with it a whole host of new, arguably larger issues; most notably, the

lack of biofidelity in movement and form, and the difficulty in assessing fit and comfort which are inseparable from

mobility when evaluating EVA glove performance. Additionally, having a larger number of test subjects would also

help factor out some of these variations, however finding a larger number of test subjects with similar glove

experiences and hand sizes may become difficult to obtain.

In general, this test series identified several tasks that allowed EVA gloves to perform a number of simple and complex

motions, which helped subjects compare and comment on overall glove characteristics. If subjective feedback is

Glove Type Glove Size

Phase VI 6MA 10.7 10.3

ILC HPEG HMA 10.7 10.4

DC Phase VII Large 9.5 9.3

Phase VI 6FO 10.1 10.2

ILC HPEG HFO 10.1 9.8

DC Phase VII Small 8.7 9.0

4000 Series ZB 9.1 n/a

w/ TMG w/o TMG

Larg

e

Glo

ves

Smal

l

Glo

ves

Distance from Suit Side Wrist Disconnect to the

Index-Middle Finger Crotch (in inches)


19

indeed used as one of the main feedback tools in future tests, test designers should ensure each subject has adequate

experience in pressurized gloves, and is allowed to evaluate each glove in is a shorter timeframe. Future test sessions

may include subjects using both/all gloves to perform the same tasks in a single test session. This would most likely

eliminate any overall fatigue data on a specific glove, but may help subjects provide more useful comparative data on

specific glove differences. A separate set of test sessions would then be needed to evaluate fatigue.

The value of quantitative data in engineering evaluations is undisputable and years of study have been dedicated to

establishing a useful approach to bring into the development of EVA gloves. However, at this point in time, the

inability to obtain meaningful results from a strictly quantitative approach, has led to the recommendation to

encompass more subjective aspects into the glove evaluation process. Future glove testing will build upon the methods

developed under the glove protocol, but will shift focus towards subjective feedback which has proved to be a more

valuable tool for assessing design features and directing forward efforts.

Acknowledgments

The authors would like to thank Dan Barta (NASA) for his continual technical and financial support throughout

the planning, execution and analysis of this data. The authors would also like to thank Darwin Portiz for his

persistence, creativity and attention to detail while performing a number of statistical analyses on this test data.

Without their support none of this work would have been possible.

48th International Conference on Environmental Systems ICES-2018-116 8-12 July 2018, Albuquerque, New Mexico


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